A method is disclosed for inspecting a weld joining a first rotor disk made of nickel alloy and having an inner surface and an outer surface concentric with the rotor's longitudinal axis to a second rotor disk having an inner surface and an outer surface concentric with the rotor's longitudinal axis. The weld made of nickel alloy fills a radial gap between the rotor disks, and has a dissimilar microstructure to either of the rotor disks. The method includes forming at least one slot in the first rotor disk extending through either the inner surface or the outer surface of the first rotor disk terminating in the first rotor disk; and passing an inspection signal from the first slot to the weld to inspect the weld for defects.